Tatzelwyrm

Yes the mythic monsters look like this. These are
not edited, not photoshopped, etc.

Mythic monsters are monsters with different coloration. In
essence, they are literally shiny versions of monsters. To obtain
mythics, you must first have the Mythic Cave →

That's it. That's all you need. Having the Mythic Cave on your
mountain will unlock mythic monsters. From there, all you have to
do is breed. Mythics are randomly obtained through breeding, and
you will not know if your egg is mythic or not until you hatch it.
Once you hatch your first mythic for a specific monster, if you get
another mythic of that monster, the egg will have a different
coloration and you will know right away without needing to hatch
the egg.